SAN FRANCISCO — Hard to believe, but there was once a time when the visionaries worked for the government. Rebuilding a ruined Europe, putting a man on the moon, connecting the U.S. interior with highways — these were immense tasks undertaken by bureaucrats.

The wild dreamers these days work for technology companies. Elon Musk, not content with making the first commercially viable electric car, has plans for a trainlike system that would speed travelers at 600 mph. Mark Zuckerberg has plans to put everyone in the world in touch.

And now Jeff Bezos, Amazon.com’s chief executive, says he is planning to take something that looks like a barbecue grill, attach eight propellers and a basket to it and use it to deliver small items to people’s houses.

Package delivery by drone is a loopy idea, far-fetched and the subject of instant mockery on Twitter — but it is hard to deny its audacity.

“I am blown away by what I see coming out of the private sector these days,” said Andrew McAfee, co-founder of the Initiative on the Digital Economy at the MIT Sloan School of Management. “All the building blocks are in place for breakthroughs: The Internet goes everywhere. Everyone has a device connected to the network. And the cost of technology experimentation is so low. We don’t need one single entity with massive resources to deliver these really cool innovations.”

The announcement by Bezos on Sunday was one of those moments when the future suddenly seems much closer. But the news also served to emphasize a less appreciated hallmark of the tech world: its masterful use of public relations.

The revelation came at the end of a “60 Minutes” feature about Amazon and its preparations for Cyber Monday, the year’s most-hyped online shopping day.

“We can do half-hour delivery,” Bezos said.

He also said the drones could carry as much as 5 pounds and could fly 10 miles from the delivery center.

“I don’t want anybody to think this is just around the corner,” he said in an uncharacteristic note of caution.

Which brought up the immediate question: Why announce it now?

Amazon is so tight-lipped it will not often confirm what happened in the past, like how many Kindles it has sold.

It seldom talks about the future.

On the show, Bezos dodged a question about whether Amazon would soon unveil a set-top box.

“I don’t want to talk about the future road map of our devices,” he said.

Unless, apparently, he did want to.

“Whether this ever amounts to anything, it was definitely a good PR move,” said Tory Patrick, leader of the retail technology practice at Walker Sands, a consultancy.

“It’s Cyber Monday and Amazon is on the brain.”

Beyond that — beyond Amazon’s meteoric stock price, its capacity to bring more goodies to more people in less time, its ceaseless innovation, its ability to make other retailers look hapless — the company is enduring an unusual period of criticism.

Its success is breeding anger.

Amazon warehouse workers are striking in Germany. The French are proposing to restrain the company with a law that forbids discounting on books.

And in Britain, sending an undercover reporter to an Amazon warehouse is becoming routine.

The most recent such investigation — which offered an indictment not only of Amazon but also of the culture that makes it such a success — was published last weekend in The Guardian.

Her fellow workers at Amazon, Carole Cadwalladr wrote, used to be builders, hospitality managers, marketing graduates, technicians, carpenters and electricians.

“They owned their own businesses, and they were made redundant,” Cadwalladr added.

“Or the business went bust. Or they had a stroke. Or their contract ended. They are people who had skilled jobs, or professional jobs, or just better-paying jobs. And now they work for Amazon, earning the minimum wage, and most of them are grateful to have that.”

In the United States, any resistance is much more muted.

But Amazon fought back hard this fall against a new book, “The Everything Store” by Brad Stone, accusing it of containing an unbalanced depiction of the company as a brutal place to work.

“The timing is interesting,” said Sucharita Mulpuru, a Forrester analyst. “The drones could be a game-changer — 20 years from now.”

An Amazon Web page unveiled immediately after the “60 Minutes” broadcast was much more bold about the drone delivery service, which is called Prime Air.

“We’ll be ready to enter commercial operations as soon as the necessary regulations are in place,” Amazon promised.

That, it said, meant 2015, when the Federal Aviation Administration will issue new rules for commercial drones.

The FAA needed a year merely to prepare its 74-page plan for the integration of drones into the national airspace.

Specific details on putting those rules into effect, the agency said when it released the plan last month, are still to come.

Sen. Edward Markey, D-Mass., a member of the Commerce, Science and Transportation Committee, said he was dissatisfied with the FAA plan because he felt it had scant privacy protections.

“Clear rules must be set that protect the privacy and safety of the public,” Markey said in a statement released Monday.

Jaron Lanier, a technology skeptic who wrote “You Are Not a Gadget,” said the drones would encourage the sort of divisions that undermine society.

“I can easily picture a scenario where drones deliver things to upscale tech-savvy customers,” he said.

“It’s also hard to imagine delivery drones flying unmolested in restive working-class or poor areas. They’d become skeet or be ‘occupied,’ depending on the nature of the neighborhood.”

McAfee, co-author of “The Second Machine Age: Work, Progress and Prosperity in a Time of Brilliant Technologies,” said he saw more benefits. “Amazon drives a big truck to the outskirts of town, unloads the drones, and they go run a bunch of final drops,” he said. “The roads will be less crowded. You’ll have less pollution.”

Patrick, the consultant, said there was no question of what people will want.

“If Amazon can pull this off, people will say, ‘This is awesome, I can get toilet paper in 30 minutes.’ And they will.”